I doubt he identified as female. I would put the gender selection as a computer error. One report said he was shooting out from PP from the very beginning of the stand-off. So I think all along his intent was to kill responding police officers. He most likely chose PP because he was able to get into the building easily and also figured most people there would be unarmed women.
You may be on to something there. It seems to me he managed to injure an unusually high number of law enforcement officers. I don’t think the responding officers had a Rambo/hero complex going or anything. Yet somehow he managed to shoot what, 5, killing one. Could be that was his objective all along.